VALES – IV. Exploring the transition of star formation efficiencies between normal and starburst galaxies using APEX/SEPIA Band-5 and ALMA at low redshift. Issue 1 (8th December 2017)

• Record Type: Journal Article
• Authors: Cheng, C; Ibar, E; Hughes, T M; Villanueva, V; Leiton, R; Orellana, G; Muñoz Arancibia, A; Lu, N; Xu, C K; Willmer, C N A; Huang, J; Cao, T; Yang, C; Xue, Y Q; Torstensson, K
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 475:Issue 1(2018)
• Page Start: 248
• Page End: 256
• Publication Date: 2017-12-08
• Subjects: galaxies: ISM -- galaxies: starburst -- galaxies: star formation -- submillimetre: galaxies; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/stx3183
• Languages: English
• ISSNs: 0035-8711

Abstract

Abstract: In this work, we present new the Swedish-ESO PI receiver for the Atacama Pathfinder Experiment APEX/SEPIA Band-5 observations targeting the CO ( J = 2–1) emission line of 24 Herschel-detected galaxies at z = 0.1–0.2. Combining this sample with our recent new Valparaíso ALMA Line Emission Survey (VALES), we investigate the star formation efficiencies [SFEs = star formation rate (SFR)/$M_{\rm H_{2}}$ ] of galaxies at low redshift. We find the SFE of our sample bridges the gap between normal star-forming galaxies and Ultra-Luminous Infrared Galaxies (ULIRGs), which are thought to be triggered by different star formation modes. Considering the SFE΄ as the SFR and the $L^{\prime }_{\rm CO}$ ratio, our data show a continuous and smooth increment as a function of infrared luminosity (or star formation rate) with a scatter about 0.5 dex, instead of a steep jump with a bimodal behaviour. This result is due to the use of a sample with a much larger range of sSFR/sSFRms using LIRGs, with luminosities covering the range between normal and ULIRGs. We conclude that the main parameters controlling the scatter of the SFE in star-forming galaxies are the systematic uncertainty of the αCO conversion factor, the gas fraction, and physical size.